<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>首页</title>
    <link rel="stylesheet" href="/style.css">
</head>
<body>
<h5>你的账户余额是：<span id="amount">100</span></h5>
<button id="button">付款一元钱</button>
<script>
    button.addEventListener('click',(e)=>{
        let n=amount.innerText;  //string
        let number=parseInt(n,10);//number
        let newNumber=number-1;
        amount.innerText=newNumber;

    })
</script>
</body>
</html>